Data Storage Device Capable of Preventing a Data Retention Fail of a Nonvolatile Memory Device and Operating Method Thereof

1. A data storage device comprising: a nonvolatile memory device including a plurality of pages; and a control unit suitable for: selecting a first page for determining a retention fail among pages of a memory block which has a wear-leveling value smaller than an average, controlling the nonvolatile memory device for performing a first read operation to the first page of the nonvolatile memory device according to a read voltage, adjusting the read voltage based on a number of error bits in read-out data according to the read voltage when the retention fail is determined to occur in the first page, performing a second read operation to the first page according to the adjusted read voltage to determine whether another retention fail is likely to occur in a re-program operation, and performing the re-program operation to the first page based on a number of on cells as a result of the second read operation according to the adjusted read voltage.

2. The data storage device according to claim 1 , wherein the control unit controls the nonvolatile memory device to adjust the read voltage when the number of the error bits of the read-out data is equal to or larger than a first reference value.

3. The data storage device according to claim 1 , wherein the control unit controls the nonvolatile memory device to perform the re-program operation to the first page when the number of on cells is equal to or larger than a second reference value.

4. The data storage device according to claim 1 , wherein the control unit controls the nonvolatile memory device to perform the re-program operation by performing an error correction operation to the read-out data according to the read voltage and a program operation to error-corrected data.

5. The data storage device according to claim 4 , wherein the control unit controls the nonvolatile memory device to perform the program operation to the error-corrected data by programming the error-corrected data into the first page.

6. The data storage device according to claim 4 , wherein the control unit controls the nonvolatile memory device to perform the program operation to the error-corrected data by programming the error-corrected data into a second page.

7. The data storage device according to claim 1 , wherein the control unit controls the nonvolatile memory device to skip the re-program operation to the first page when the number of on cells is smaller than a second reference value.

8. The data storage device according to claim 1 , wherein the control unit controls the nonvolatile memory device to adjust the read voltage when the number of the error bits of the read-out data is equal to or larger than a first reference value and the error bits are correctable.

9. A method for operating a data storage device including a plurality of pages, the method comprising: selecting a first page for determining a retention fail among pages of a memory block which has a wear-leveling value smaller than an average; performing a first read operation to the first page of the nonvolatile memory device according to a read voltage; adjusting the read voltage based on a number of error bits in read-out data according to the read voltage when the retention fail is determined to occur in the first page; performing a second read operation to the first page according to the adjusted read voltage to determine whether another retention fail is likely to occur in a re-program operation; and performing the re-program operation to the first page based on a number of on cells as a result of the second read operation according to the adjusted read voltage.

10. The method according to claim 9 , wherein the adjusting of the read voltage is performed when the number of the error bits of the read-out data is equal to or larger than a first reference value.

11. The method according to claim 9 , wherein the re-program operation to the first page is performed when the number of on cells is equal to or larger than a second reference value.

12. The method according to claim 9 , wherein the performing of the re-program operation includes performing an error correction operation to the read-out data according to the read voltage and a program operation to error-corrected data.

13. The method according to claim 12 , wherein the performing of the program operation to the error-corrected data includes programming the error-corrected data into the first page.

14. The method according to claim 12 , wherein the performing of the program operation to the error-corrected data includes programming the error-corrected data into a second page.

15. The method according to claim 9 , wherein the performing of the re-program operation to the first page includes skipping the re-program operation to the first page when the number of on cells is smaller than a second reference value.

16. The method according to claim 9 , wherein the adjusting of the read voltage is performed when the number of the error bits of the read-out data is equal to or larger than a first reference value and the error bits are correctable.